JP2006015193A - Coating film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film forming method which can coat uniformly and thinly an inorganic building material having an irregular protrusion and recess of several meters to over ten meters, formed according to a design, with a top coat. <P>SOLUTION: The coating film forming method is comprised of applying a sealer containing Shirasu balloons having an average of a particle diameter of 10-500 μm and acrylic resin water dispersions to the inorganic building material to dry, thereby forming the coating film having the protrusion and recess formed by the Shirasu balloons on the inorganic building material, and applying the top coat to dry. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a coating film, which enables a top coat to be uniformly and thinly coated on the surface of an inorganic building material having irregular irregularities.

  In recent years, various building materials that can be used for buildings such as houses are required to have durability that does not need to be repaired for a long time after a new construction. In response to such a demand, for example, an inorganic building material having excellent durability is used as a building material for interior and exterior.

  In general, the inorganic building material is often used by coating its surface with a paint. In particular, the top coating is required to form a coating film excellent in weather resistance from the viewpoint of protecting the inorganic building material. . Examples of the top coating material include silicon-based paints and fluorine-based paints (see, for example, Patent Document 1). However, it is not appropriate to apply these paints to inorganic building materials thickly from the viewpoint of environmental load, and it is preferable to apply thin coatings to inorganic building materials. However, most of the inorganic building materials used for roofs and the like have irregular, uneven patterns of several mm to several tens of mm derived from the design, so that the film thickness of such inorganic building materials is reduced. When the top coating is applied, the film thickness becomes uneven between the concave portion and the convex portion of the inorganic building material, and there may be a portion where the top coating is not yet applied.

Japanese Patent Application Laid-Open No. 11-209663

  The problem to be solved by the present invention is to provide a coating film forming method capable of uniformly and thinly applying a top coating to an inorganic building material having irregular irregularities derived from design properties.

  As the inventors proceeded with studies to solve the above problems, an undercoating paint containing a shirasu balloon having an average particle diameter of 10 to 500 μm was previously applied to an inorganic building material and dried, and the surface of the inorganic building material was When a coating film having minute irregularities due to the shirasu balloon was formed and then the top coat was applied, the minute irregularities due to the shirasu balloon retained the top coating uniformly, and irregularities derived from the design of inorganic building materials It was found that a uniform and thin coating film can be formed on the part.

  That is, the present invention results from the shirasu balloon on the inorganic building material by applying the shirasu balloon having an average particle diameter of 10 to 500 μm and an undercoating paint containing an acrylic resin aqueous dispersion to the inorganic building material and drying it. The present invention relates to a coating film forming method in which a coating film having irregularities is formed, and then a top coating is applied and dried.

  According to the method for forming a coating film of the present invention, a top coating can be uniformly and thinly applied to an inorganic building material having an irregular uneven surface derived from design.

  The method for forming a coating film according to the present invention comprises applying an undercoating paint comprising a shirasu balloon having an average particle diameter of 10 to 500 μm and an acrylic resin aqueous dispersion onto an inorganic building material and drying the shirasu on the inorganic building material. A coating film having unevenness caused by the balloon is formed, and then a top coating is applied and dried.

  Examples of a method for applying an undercoating material comprising an inorganic building material containing a shirasu balloon having an average particle diameter of 10 to 500 μm and an acrylic resin aqueous dispersion include a brush coating method, a flow coater method, a curtain coater method, and a dip coating method. And a flow coating method. In particular, it is preferable to apply the coating by a flow coater method in which the coating efficiency is high and the shirasu balloon having an average particle diameter of 10 to 500 μm is not clogged.

  A drying method after applying an undercoating paint containing an Shirasu balloon having an average particle diameter of 10 to 500 μm and an acrylic resin aqueous dispersion to the inorganic building material can be appropriately selected according to the type of the inorganic building material, for example, Examples thereof include a method of leaving at room temperature for about 1 day to 10 days, or heating in a temperature range of 40 ° C. to 250 ° C. for about 10 seconds to 2 hours.

  The film thickness of the coating film obtained by using an undercoat paint comprising a shirasu balloon having an average particle diameter of 10 to 500 μm and an acrylic resin aqueous dispersion is preferably in the range of 10 μm to 200 μm, and 10 μm to 100 μm. More preferably. However, it is necessary that the surface of the obtained coating film has irregularities due to the shirasu balloon. These fine irregularities can keep the top coat uniformly thin on the undercoat film. Accordingly, the film thickness of the concave portion of the coating film having unevenness caused by the shirasu balloon obtained by using the shirasu balloon having an average particle size of 10 to 500 μm and the squirrel balloon containing the acrylic resin aqueous dispersion is determined as follows. The average particle diameter of the balloon is 1/10 to 3/4, more preferably in the range of 10 μm to 200 μm, still more preferably 10 μm to 100 μm. Thereby, it is possible not only to shield the alkali component that exudes from the inorganic building material, but also to uniformly and thinly apply the top coating.

  Examples of a method for applying a top coating on a cured coating obtained using a squirrel balloon having an average particle diameter of 10 to 500 μm and an undercoating coating containing an acrylic resin aqueous dispersion include, for example, brush coating and a flow coater method. And coating methods such as curtain coater method, dip coating method, flow coating method and spray method. In particular, it is preferable to apply the coating by a flow coater method or a curtain coater method with high coating efficiency.

  The drying method after the top coating is applied can be appropriately selected according to the type of inorganic building material to be used, the composition of the top coating, and the like. For example, the drying method can be left at room temperature for about 1 to 10 days, or 40 to 250 ° C. A method of heating in the temperature range for about 10 seconds to 2 hours is mentioned.

  The film thickness of the coating film obtained by using the top coating material is preferably 3 μm to 30 μm, more preferably 5 μm to 20 μm from the balance between the reduction in the amount of the top coating material used and the weather resistance of the coating film obtained. 5 to 15 μm is more preferable.

  Next, the undercoat paint used in the present invention will be described in detail.

  The undercoat used in the present invention contains a shirasu balloon having an average particle diameter of 10 to 500 μm and an acrylic resin aqueous dispersion.

A shirasu balloon is a fine hollow glass sphere having a chemical composition such as SiO ₂ or Al ₂ O ₃ , for example, volcanic glass particles contained in volcanic glassy deposits widely distributed in Japan. It can be produced by firing and foaming at a high temperature of 1000 ° C.

  Some Shirasu balloons have different average particle sizes, but in the present invention, those having an average particle size of 10 to 500 μm must be used. When the average particle diameter is less than 10 μm, it is difficult to form a coating film having unevenness due to the shirasu balloon because the average particle diameter is too small. Moreover, when the average particle diameter exceeds 500 μm, the unevenness caused by the shirasu balloon is large, and it becomes difficult to uniformly apply the top coating. At this time, the film thickness of the undercoat paint may be increased, but it is not preferable to increase the film thickness from the viewpoint of low environmental load.

  The average particle size of the shirasu balloon can be arbitrarily selected according to the film thickness of the undercoat paint because it is necessary to form a coating film having irregularities due to the shirasu balloon on the surface of the inorganic building material. In addition, the average particle diameter as used in the field of this invention means a volume average median diameter, for example, can be measured with the laser diffraction type particle size measuring apparatus (SALD-2000) by Shimadzu Corporation.

  The shirasu balloon preferably has a bulk density of 0.1 to 0.5. The undercoating paint containing a shirasu balloon having a bulk density in such a range is excellent in stability because the shirasu balloon is difficult to precipitate or agglomerate and solidify.

  The shirasu balloon is preferably contained in an amount of 0.1 to 40% by weight, more preferably 0.5 to 30% by weight based on the solid content in the undercoat paint. More preferably, it is contained in an amount of 20% to 20% by weight. As a result, a top coat described later can be uniformly and thinly applied to the inorganic building material, and the coating workability is also improved.

  The acrylic resin aqueous dispersion used for the undercoat paint is obtained by dispersing an acrylic resin in an aqueous medium.

  Examples of the acrylic resin aqueous dispersion include an acrylic resin emulsion and an aqueous dispersion of an acrylic resin having a hydrophilic group.

  The acrylic resin emulsion can be produced by an emulsion polymerization method in the presence of an emulsifier in a conventional medium using an acrylic resin.

  Examples of the acrylic monomer include (meth) acrylic acid and alkali metal salts thereof, various esters of (meth) acrylic acid, (meth) acrylonitrile, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl ( Examples include meth) acrylate, 3- (meth) acryloylpropyltrimethoxysilane, 2-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

  Examples of the emulsifier that can be used in the emulsion polymerization method include nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene copolymer, alkyl sulfate ester salts, and alkylbenzene sulfonic acid. Anionic emulsifiers such as salts, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, and cationic emulsifiers such as quaternary ammonium salts. The emulsifier is preferably used in the range of 0.1 to 10% by weight of the total weight of the acrylic monomer, and from the viewpoint of water resistance of the resulting coating film, 0.1 to 5% by weight. It is more preferable that

  The acrylic monomer is preferably polymerized by a radical emulsion polymerization method using a radical polymerization initiator. Examples of the radical polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, and the like. And organic peroxides such as benzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, and the like. Moreover, the redox-type initiator etc. which combined peroxides, such as cumene hydroperoxide, and reducing agents, such as sugar-containing iron pyrophosphate, can also be used. The amount of the radical polymerization initiator used is preferably 0.01% to 5% by weight, and preferably 0.05% to 2% by weight, based on the total weight of the acrylic monomer.

  When producing the emulsion of the acrylic resin, a chain transfer agent, a pH adjuster and the like can be used in combination with the acrylic monomer, the emulsifier and the radical polymerization initiator, if necessary.

  The emulsion of the acrylic resin is preferably 5 ° C. to 100 ° C., more preferably 50 ° C. to 90 ° C. in the presence of the emulsifier in an aqueous medium of 100 wt% to 500 wt% of the total weight of the acrylic monomer. It can be produced by emulsion polymerization within a temperature range of ° C. The polymerization time at this time is preferably in the range of 0.1 hour to 10 hours.

  The aqueous dispersion of an acrylic resin having a hydrophilic group is obtained by dispersing or partially dissolving an acrylic resin having a hydrophilic group in an aqueous medium.

  The acrylic resin having a hydrophilic group is one having a hydrophilic group such as an anionic group, a cationic group, or a nonionic group.

  Examples of the anionic group include a carboxyl group, a phosphoric acid group, an acidic phosphate ester group, a phosphorous acid group, a sulfonic acid group, a sulfinic acid group, and the like, which are neutralized with a basic compound. preferable.

  Examples of basic compounds that can be used for neutralizing the anionic group include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, 2-aminoethanol, 2-dimethylaminoethanol, ammonia, sodium hydroxide, Examples include potassium hydroxide, tetramethylammonium hydroxide, tetra-n-butylammonium hydroxide, and trimethylbenzylammonium hydroxide.

  Examples of the cationic group include a primary amino group, a secondary amino group, a tertiary amino group, and an ammonium hydroxide group, and those obtained by neutralizing these with an acidic compound are preferable.

  Examples of the acidic compound include formic acid, acetic acid, propionic acid, lactic acid, phosphoric acid monomethyl ester, methanesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, hydrochloric acid, sulfuric acid, and nitric acid.

  Examples of nonionic groups include those having a polyether chain such as polyoxyethylene and polyoxypropylene.

  In this invention, it is preferable to use what neutralized the acrylic resin which has a carboxyl group which is anionic group with the basic compound as an acrylic resin which has a hydrophilic group.

  The acrylic resin having a hydrophilic group can be produced, for example, by polymerizing an acrylic monomer having a hydrophilic group.

  Examples of the acrylic monomer having a hydrophilic group include various carboxyl group-containing acrylic monomers such as (meth) acrylic acid and 2-carboxyethyl (meth) acrylate, alkali metal salts thereof, and the like. -Various tertiary amino group-containing (meth) acrylamides such as dimethyl (meth) acrylamide, various tertiary amino group-containing (meth) acrylic esters such as dimethylaminoethyl (meth) acrylate, and quaternized products thereof These can be used singly or in combination of two or more. Among them, it is preferable to use (meth) acrylic acid or dimethylaminoethyl (meth) acrylate.

  As a method for producing an acrylic resin having a hydrophilic group using the acrylic monomer having the hydrophilic group, various known and usual polymerization methods can be mentioned. Among them, a solution using an organic solvent is used. The radical polymerization method is the simplest.

  Examples of the organic solvent include aliphatic or alicyclic hydrocarbon solvents such as n-hexane, n-heptane, n-octane, cyclohexane and cyclopentane; aromatic hydrocarbon solvents such as toluene, xylene and ethylbenzene; ethyl acetate, Ester solvents such as n-butyl acetate, n-amyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, methanol, ethanol, iso-propanol, n-butanol, iso-butanol, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, propylene glycol monomethyl ether, propylene glycol mono-n-propyl Alcohol solvents such as pill ether and diethylene glycol monobutyl ether, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone and cyclohexanone, dimethoxyethane, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether And ether solvents such as diethylene glycol dibutyl ether, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and ethylene carbonate.

  Examples of the radical polymerization initiator that can be used in the solution radical polymerization method include azo compounds such as 2,2′-azobis (isobutylnitryl) and 2,2′-azobis (2,4-dimethylvaleronitrile); And peroxides such as butyl peroxypivalate, tert-butyl peroxybenzoate, and tert-butyl peroxy-2-ethylhexanoate.

  If necessary, an acrylic monomer copolymerizable therewith can be used in combination with the acrylic monomer having a hydrophilic group. Examples of the acrylic monomer copolymerizable with the acrylic monomer having a hydrophilic group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and cyclohexyl (meth) acrylate. Examples thereof include alkyl esters of (meth) acrylic acid.

  The obtained acrylic resin having a hydrophilic group preferably has a number average molecular weight of 500 to 200,000, more preferably 700 to 100,000, from the viewpoint of water resistance of the coating film and paint viscosity. More preferred are those having 50,000 to 50,000.

  Examples of a method for dispersing the obtained acrylic resin having a hydrophilic group in an aqueous medium include known and commonly used methods. Among them, it is preferable to disperse by an inversion emulsification method.

  The phase inversion emulsification method is a method in which the hydrophilic group of the acrylic resin is neutralized with a basic compound or an acidic compound, if necessary, and then dispersed in an aqueous medium.

  When the hydrophilic group of the acrylic resin is a cationic group, after the acrylic resin having a cationic group is dissolved in an organic solvent, the cationic group is neutralized with the basic compound, and then water is added. The method is preferred.

  When the hydrophilic group of the acrylic resin is an anionic group, the acrylic resin having an anionic group is dissolved in an organic solvent, the anionic group is neutralized with the acidic compound, and then water is added. Is preferred.

  In the phase inversion emulsification method, an emulsifier can be used as necessary within the range of achieving the object of the present invention.

  Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene copolymer, alkyl sulfate ester salt, alkylbenzene sulfonate, polyoxyethylene alkyl ether sulfate. Anionic emulsifiers such as ester salts and polyoxyethylene alkylphenyl ether sulfate esters, and cationic emulsifiers such as quaternary ammonium salts.

  The aqueous medium may contain an organic solvent from the viewpoint of improving film formability and paintability.

  As the organic solvent, those similar to those exemplified as the organic solvent that can be used in the solution radical polymerization method can be used, and among them, ester solvents, alcohol solvents, ketone solvents, ether solvents are used. It is preferable. The organic solvent contained in the aqueous medium may be used alone or in combination of two or more. The use ratio thereof is preferably 40% by weight or less, more preferably 20% by weight or less of the aqueous medium, and 10% by weight. % Or less is more preferable.

  The aqueous dispersion of the acrylic resin thus obtained preferably contains an aqueous medium in an amount of 100% to 500% by weight of the acrylic resin.

  The undercoat paint can be produced by mixing the acrylic resin aqueous dispersion and the shirasu balloon.

  Examples of the mixing method include known and commonly used methods using a resolver, a rotary stirrer with impeller type blades, and a rotary stirrer with propeller type blades.

  The undercoat paint thus obtained may be a clear paint containing no pigment or a colored paint containing a pigment.

  Examples of pigments include organic pigments such as perylene, quinacridone, anthraquinone, isoindolinone, isoindoline, diketopyrrolopyrrole, dioxazine, phthalocyanine blue, and phthalocyanine green; carbon black, titanium oxide, iron oxide, titanium yellow, copper chromium Inorganic pigments such as black are listed. Of these, extender pigments such as potassium carbonate, clay, talc and barium sulfate, and flake pigments such as aluminum flakes and pearl mica can also be used.

  A curing agent can be used in the undercoat paint as necessary. Such a curing agent is a compound having at least one functional group that reacts with the functional group of the acrylic resin contained in the undercoat paint.

  When the functional group of the acrylic resin is a carboxyl group, examples of the curing agent include compounds having at least two epoxy groups and cyclocarbonate groups. When the functional group possessed by the acrylic resin is a hydroxyl group, a compound containing at least two N-hydroxymethylamino groups or isocyanate groups can be mentioned.

  For the undercoat paint, for example, a curing catalyst, a flow modifier, a leveling agent, a rheology control agent, an ultraviolet absorber, an infrared absorber, an antioxidant, a plasticizer, and the like can be used as necessary.

  Next, an inorganic building material for applying the undercoat paint will be described.

  Examples of the inorganic building material used in the present invention include asbestos cement, asbestos cement, concrete, lightweight cellular concrete (ALC), flexible board, mortar, slate, gypsum, ceramics, brick, and tile. Of these, asbestos cement and asbestos cement are preferable because they can be used as a roofing material that requires excellent weather resistance.

  The inorganic building material may be provided with a concavo-convex pattern of several mm to several tens of mm for the purpose of imparting design properties. Even with such an inorganic building material, a thin and uniform coating film can be formed according to the coating film forming method of the present invention.

  Next, the top coat used in the present invention will be described.

  As the top coat used in the present invention, any of the known and commonly used solvent-based paints, water-based paints such as water-dispersible paints and water-soluble paints can be used. Since the inorganic building material can be mainly used as a building material, it is preferable to use a silicon-based paint capable of forming a coating film having excellent weather resistance as a top coating to be applied thereto. Especially, it is more preferable to use the coating material which uses as a binder the vinyl polymer which has a structural unit derived from polysiloxane in a side chain from a viewpoint of the crack resistance of a coating film.

  Examples of the silicon-based paint include pure silicon paint made of 100% polysiloxane, silicon-modified alkyd paint, silicon-modified polyester paint, silicon-modified acrylic paint, and silicon-modified urethane paint. Of these, a paint containing a resin composed of polysiloxane and a vinyl polymer is preferable from the viewpoint of the weather resistance of the resulting coating film, and a vinyl-based polymer having a polysiloxane-derived structural unit in the side chain. The coalescence is more preferable from the viewpoint of high weather resistance.

  The vinyl polymer having a structural unit derived from polysiloxane in the side chain is a vinyl polymer in which polysiloxane is chemically grafted as a side chain. The vinyl polymer having a structural unit derived from polysiloxane in the side chain can be used for a solvent-based paint or an aqueous paint, but is preferably used for an aqueous paint from the viewpoint of low environmental load.

  The vinyl polymer having a structural unit derived from polysiloxane in the side chain has a structure represented by the following structural formula (S-1) formed when the polysiloxane and the vinyl polymer are bonded together. From the viewpoint of

  The polysiloxane has a hydroxyl group bonded to a silicon atom and / or a hydrolyzable group bonded to a silicon atom, generally called a silanol group.

  Examples of hydrolyzable groups include halogen atoms, alkoxy groups, substituted alkoxy groups, acyloxy groups, phenoxy groups, mercapto groups, amino groups, amide groups, aminooxy groups, iminooxy groups, alkenyloxy groups, and the like. Silanol groups can be generated by hydrolysis.

  As polysiloxane, the hydrolysis condensate or partial hydrolysis condensate of the silane compound shown, for example by general formula (S-2) is mentioned.

[Where R ¹ in the formula may not have have a substituent, an alkyl group, a cycloalkyl group, an aryl group, a monovalent organic group comprising aralkyl or alkenyl group, R ² Represents a halogen atom, an alkoxy group, a substituted alkoxy group, an acyloxy group, a phenoxy group, a mercapto group, an amino group, an amide group, an aminooxy group, an iminooxy group or an alkenyloxy group. a is 1 or 2; ]

  Examples of the silane compound represented by the general formula (S-2) include methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-butoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, and iso-butyltrimethoxy. Organotrialkoxysilanes such as silane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane or 3- (meth) acryloyloxypropyltrimethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi Diolga such as n-butoxysilane, diethyldimethoxysilane, diphenyldimethoxysilane, methylcyclohexyldimethoxysilane or methylphenyldimethoxysilane Dialkoxysilanes; various chlorosilanes such as methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, vinyltrichlorosilane, 3- (meth) acryloyloxypropyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane or diphenyldichlorosilane; Among them, it is preferable to use organotrialkoxysilane or diorganodialkoxysilane.

  Examples of the vinyl polymer that reacts with the polysiloxane include a vinyl polymer having a functional group capable of reacting with the polysiloxane. Examples of such a functional group include a hydroxyl group and a hydrolyzable silyl group, and a hydrolyzable silyl group is preferable from the viewpoint that weatherability can be improved by introducing the structure represented by the structural formula (S-1).

  Examples of the vinyl polymer having a hydrolyzable silyl group include an acrylic polymer, a fluoroolefin polymer, a vinyl ester polymer, an aromatic vinyl polymer, a polyolefin polymer having a hydrolyzable silyl group. Among them, it is preferable to use an acrylic polymer having a hydrolyzable silyl group.

  The hydrolyzable silyl group possessed by the vinyl polymer is a functional group represented by the following general formula (S-3). The hydrolyzable silyl group is particularly preferably introduced into the side chain of the vinyl polymer.

[Wherein R ³ is a monovalent organic group such as an alkyl group, an aryl group or an aralkyl group, and R ⁴ is a halogen atom, an alkoxy group, an acyloxy group, a phenoxy group, an aryloxy group, a mercapto group, an amino group, Represents an amide group, an aminooxy group, an iminooxy group or an alkenyloxy group; b represents 0, 1 or 2; ]

  As a method for introducing the hydrolyzable silyl group represented by the general formula (S-3) into the vinyl polymer, various known and conventional methods can be applied. One simple method includes a method in which a vinyl monomer having a hydrolyzable silyl group and another vinyl polymer copolymerizable with these are polymerized by a solution radical polymerization method.

  Examples of the vinyl monomer having a hydrolyzable silyl group include 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, and 3- (meth) acryloyloxypropyl. Examples include methyldimethoxysilane.

  Examples of the vinyl polymer copolymerizable with the hydrolyzable silyl group-containing vinyl monomer include (meth) acrylic acid and alkyl esters thereof, (meth) acrylonitrile, N, N-dimethyl (meth). Examples include acrylamide, 2-hydroxyethyl (meth) acrylate, 3- (meth) acryloylpropyltrimethoxysilane, 2-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

  The vinyl polymer having a structural unit derived from polysiloxane in the side chain is preferably produced by the following production method (1), (2), (3) or (4).

  (1) A separately produced vinyl polymer having a hydrolyzable silyl group in the side chain and a polysiloxane obtained by hydrolysis condensation reaction of the silane compound represented by the general formula (S-2), A method in which a polysiloxane is grafted to a side chain of the vinyl polymer by a condensation reaction in an organic solvent.

  (2) Polysiloxane obtained by hydrolytic condensation of the silane compound represented by the general formula (S-2) in the presence of a vinyl polymer having a hydrolyzable silyl group in the side chain in an organic solvent. Is a method of grafting onto the side chain of the vinyl polymer.

  (3) A vinyl heavy polymer having a hydrolyzable silyl group in the side chain in the presence of polysiloxane obtained by hydrolytic condensation reaction of the silane compound represented by the general formula (S-2) in an organic solvent. A method in which polysiloxane is grafted to a side chain of the vinyl polymer in the course of preparing a coalescence.

  (4) Reaction of preparing polysiloxane obtained by hydrolytic condensation reaction of the silane compound represented by the general formula (S-2) in an organic solvent, and vinyl having a hydrolyzable silyl group in the side chain A method in which polysiloxane is grafted to a side chain of a vinyl polymer by simultaneously performing a reaction for preparing a polymer in the same reaction system.

  When a vinyl polymer having a polysiloxane-derived structural unit in the side chain is used in an aqueous coating material, it is necessary to further introduce a hydrophilic group.

  The vinyl polymer having a structural unit derived from polysiloxane in the side chain and having a hydrophilic group is obtained by converting the vinyl polymer having a hydrolyzable silyl group and a hydrophilic group to the side of the hydrolyzable silyl group. It can be produced by grafting polysiloxane by the same production method as in the above (1) to (4) except that it is used instead of the vinyl polymer in the chain.

  The obtained water-based paint comprising a polysiloxane-derived structural unit in the side chain and containing a vinyl polymer having a hydrophilic group, neutralizes the hydrophilic group as necessary, and an aqueous medium It can be produced by dissolving or dispersing in.

  The hydrophilic group of the vinyl polymer having both a hydrolyzable silyl group and a hydrophilic group is the same as that already exemplified as the water-dispersible acrylic resin used in the undercoat paint. can do. Among these, an anionic group is preferably used, and a carboxyl group neutralized with the basic compound is more preferably used.

  As a vinyl polymer having a polysiloxane-derived structural unit in the side chain that can be used in an aqueous coating, the following vinyl polymer (A-1) is used from the viewpoint of excellent curability and excellent long-term storage stability. It is preferable to do.

  Such a vinyl polymer (A-1) is obtained by reacting an organotrialkoxysilane represented by the general formula (S-4) with a polysiloxane having a silicon atom described in the following (5) and / or (6). The structural unit derived from polysiloxane (p-1) obtained in this way and an anionic group are present in the side chain.

  (5) A silicon atom to which a hydrolyzable group or hydroxyl group and an organic group having 3 or more carbon atoms are bonded. (6) A silicon atom in which one hydrolyzable group or hydroxyl group and two methyl groups or ethyl groups are bonded.

  The vinyl polymer (A-1), for example, produces a vinyl polymer having a structural unit derived from polysiloxane having (5) and / or (6) in the side chain and an anionic group, and then It can be produced by reacting a polysiloxane which is a hydrolysis condensate or a partial hydrolysis condensate of an alkoxysilane containing an organotrialkoxysilane represented by the following general formula (S-4).

[In the formula, R ⁵ represents an alkyl group having 3 or less carbon atoms, and R ⁶ represents an alkyl group having 4 or less carbon atoms. ]

  The side chain derived from a polysiloxane having an organic group having 3 or more carbon atoms or two methyl groups or ethyl groups suppresses the reactivity of hydrolyzable groups and hydroxyl groups due to its steric hindrance. The long-term storage stability of the paint can be improved.

  On the other hand, the polysiloxane obtained using the organotrialkoxysilane represented by the general formula (S-4) does not have a functional group having a large steric hindrance that can suppress the reactivity, and as a result, Curability can be improved.

  Examples of the organic group having 3 or more carbon atoms include an alkyl group, a cycloalkyl group, a phenyl group, an aryl group, and an aralkyl group having 3 or more carbon atoms. 18 alkyl groups, cycloalkyl groups and aryl groups are preferred, and an iso-butyl group, a cyclohexyl group and a phenyl group are more preferred.

  The top coating composition used in the present invention may be one in which a curing agent is used in combination with a vinyl polymer having a structural unit derived from polysiloxane in the side chain.

  The curing agent can be appropriately selected depending on the type of functional group contained in the vinyl polymer having a structural unit derived from polysiloxane in the side chain, but it is bonded to a hydroxyl group bonded to a silicon atom and / or bonded to a silicon atom. Compound having hydrolyzable group, compound having both epoxy group and hydrolyzable group bonded to silicon atom in one molecule, polyisocyanate compound, block polyisocyanate compound, polyepoxy compound, polyoxazoline compound, amino resin or A polyfunctional hydrazide compound etc. are mentioned, These can be used individually or in combination of 2 or more types.

  The topcoat paint may be a clear paint containing no pigment or a colored paint containing a pigment. As such pigments, the same pigments as those already enumerated as those that can be used for the undercoat paint can be used.

  If necessary, additives such as a curing catalyst, a flow modifier, a leveling agent, a rheology control agent, an ultraviolet absorber, an infrared absorber, an antioxidant, and a plasticizer can be used for the top coat.

Reference Example 1 [Preparation Example of Polysiloxane]
A reaction vessel equipped with a thermometer, a reflux condenser, and a dropping funnel was charged with 1,000 parts by weight of methyltrimethoxysilane (hereinafter abbreviated as MTMS), and the temperature was raised to 60 ° C. Then, a mixture of 0.12 parts by weight of “A-3” (iso-propyl acid phosphate manufactured by Sakai Chemical Co., Ltd.) and 146 parts by weight of deionized water was added dropwise at the same temperature for 5 minutes. Subsequently, it heated up to 80 degreeC and stirred at the same temperature for 4 hours. Subsequently, it distilled under reduced pressure at 40-60 degreeC under pressure reduction of 10-300 mmHg for 4 hours, and the solution of the polysiloxane of the number average molecular weight 900 (nonvolatile content 70 weight%) was obtained by removing the produced | generated methanol and water. Hereinafter, this is abbreviated as polysiloxane (p-1-1).

The polysiloxane (p-1-1) was analyzed by nuclear magnetic resonance analysis ( ¹ H-NMR). As a result, the polysiloxane (p-1-1) was composed of a hydroxyl group bonded to a silicon atom and a methoxy bonded to a silicon atom. It was confirmed that the polysiloxane had both groups.

  Reference Example 2 [Preparation Example of Polysiloxane-Acrylic Composite Resin Aqueous Dispersion]

  In a reaction vessel equipped with a thermometer, a reflux condenser, a stirrer, a dropping funnel and a nitrogen introduction tube, 87.7 parts by weight of phenyltrimethoxysilane (hereinafter abbreviated as PTMS) and dimethyldimethoxysilane (hereinafter abbreviated as DMDMS). ) And 21 parts by weight of propylene glycol-mono-n-propyl ether (hereinafter abbreviated as PnP) were charged, and the temperature was raised to 80 ° C. under a stream of nitrogen gas. Next, 32 parts by weight of methyl methacrylate (hereinafter abbreviated as MMA), 24 parts by weight of n-butyl methacrylate (hereinafter abbreviated as BMA), and 13 of n-butyl acrylate (hereinafter abbreviated as BA) at the same temperature. A monomer mixture comprising 6 parts by weight, 2.4 parts by weight of 3-methacryloyloxypropyltrimethoxysilane (hereinafter abbreviated as MPTMS) and 8 parts by weight of acrylic acid (hereinafter abbreviated as AA), and 4 PnP A mixture consisting of parts by weight and 4 parts by weight of tert-butylperoxy-2-ethylhexanoate (hereinafter abbreviated as TBPOEH) was separately added dropwise over 4 hours.

After completion of the dropwise addition, the mixture is stirred at the same temperature for 2 hours, and then a mixture of 1.42 parts by weight of “A-3” and 39.86 parts by weight of deionized water is added dropwise over 5 minutes, and the mixture is further stirred for 4 hours. Then, PTMS and DDMMS in the reaction vessel and an acrylic polymer obtained by polymerizing the monomer mixture were subjected to a cohydrolysis condensation reaction. When the obtained reaction solution was analyzed by ¹ H-NMR, it was found that the methoxysilyl group of acrylic polymer, PTMS and DMDMS was 100% hydrolyzed.

  Next, 11.2 parts by weight of triethylamine was added dropwise over 5 minutes while stirring the obtained reaction solution at room temperature. Next, 42.39 parts by weight of the polysiloxane (p-1-1) prepared in Reference Example 1 was added dropwise over 5 minutes, and then 275 parts by weight of deionized water was added dropwise over 10 minutes. Finally, distilled under reduced pressure at 40 to 60 ° C. under reduced pressure of 10 to 300 mmHg for 4 hours to remove a part of the generated methanol and water, and an aqueous dispersion of polysiloxane-acrylic composite resin having a nonvolatile content of 40.0% by weight A liquid (W-1-1) was obtained.

Reference Example 3 [Preparation Example 1 for Topcoat]
100 parts by weight of the polysiloxane-acrylic composite resin aqueous dispersion (W-1-1) obtained in Reference Example 2 and “DISPERS COLOR HG-901” [black pigment paste manufactured by Dainippon Ink & Chemicals, Inc. , Pigment weight concentration (PWC): 71.4 wt%, non-volatile content: 35 wt%] and 32.5 parts by weight of water were shaken with a paint conditioner for 30 minutes, A black top coat (top coat-1) having a PWC of 3% by weight and a non-volatile content of 30% by weight was prepared.

Reference Example 4 [Preparation Example 2 for Topcoat]
87.5 parts by weight of the polysiloxane-acrylic composite resin aqueous dispersion (W-1-1) obtained in Reference Example 2, 5.0 parts by weight of “DISPERS COLOR HG-901”, and 40 parts by weight of water The mixture with the part was shaken with a paint conditioner for 30 minutes. Next, by blending 5.0 parts by weight of 3-glycidoxypropyltrimethoxysilane as a curing agent, a black top coat (top coat-2) having a PWC of 3% by weight and a non-volatile content of 30% by weight was prepared. .

Reference Example 5 (Example of preparation of acrylic resin aqueous dispersion)
In a reaction vessel equipped with a thermometer, a reflux condenser, a stirrer, a dropping funnel and a nitrogen introduction tube, 400 parts by weight of deionized exchange water and New Coal 707SF (an anionic emulsifier with a solid content of 30% by weight manufactured by Nippon Emulsifier Co., Ltd.) The parts were charged, stirring was started, and the temperature was raised to 80 ° C. 0.35 parts by weight of sodium persulfate was charged, and while maintaining the reaction temperature at 78 ° C to 80 ° C, 70 parts by weight of deionized exchange water prepared separately, 17.5 parts by weight of New Coal 707SF, 122.5 parts by weight of BA Separately, a monomer mixture consisting of 218.8 parts by weight of MMA and 8.8 parts by weight of methacrylic acid, and a mixture of 0.35 parts by weight of sodium persulfate and 7 parts by weight of deionized water, The solution was added dropwise over 3 hours. While maintaining the same temperature, a mixture of 1.05 parts by weight of sodium persulfate and 28 parts by weight of deionized water was added, and the mixture was further maintained at the same temperature for 4 hours, and then cooled to room temperature. The pH was adjusted to 6.5 using 25% by weight aqueous ammonia, and deionized water was added to obtain an acrylic resin aqueous dispersion (W-2-1) having a nonvolatile content of 40.0% by weight.

Reference Example 6 [Preparation Example 1 for Comparative Undercoat Paint]
100 parts by weight of the acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5 and "DICTON WHITE HD-8361W" [Dai Nippon Ink Chemical Co., Ltd. white pigment paste, pigment weight concentration (PWC): 86.7% by weight, nonvolatile content: 69.2% by weight) and 40.7 parts by weight of water were shaken with a paint conditioner for 30 minutes. A comparative white base coat (ratio-1) having a non-volatile content of 10% by weight and 30% by weight was prepared.

Reference Example 7 [Preparation Example 2 for Comparative Undercoat Paint]
100 parts by weight of the acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5, 7.4 parts by weight of “DICTON WHITE HD-8361W”, “SILAX PB-20” [Co., Ltd.] The mixture of 2.2 parts by weight of Shirasu Shirasu balloon, average particle size: 600 μm, bulk density: 0.10-0.20] and 44 parts by weight of water was shaken with a paint conditioner for 30 minutes, A white undercoat paint (ratio-2) having a PWC of 10% by weight and a nonvolatile content of 30% by weight was prepared. The Shirasu balloon content ratio in the white undercoat paint (ratio-2) was 5% by weight with respect to the nonvolatile content contained in the (ratio-2).

Reference Example 8 [Preparation Example 3 for Comparative Undercoat Paint]
94.5 parts by weight of the acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5, 7.4 parts by weight of “DICTON WHITE HD-8361W”, “SILAX SFB-081” [( A mixture of 2.2 parts by weight of Shirasu Co., Ltd. Shirasu Balloon, average particle size: 8 μm, bulk density: 0.10 to 0.30, and 44 parts by weight of water is shaken with a paint conditioner for 30 minutes. Then, a white undercoat paint (ratio-3) having a PWC of 10% by weight and a non-volatile content of 30% by weight was prepared. The shirasu balloon content in the white undercoat paint (ratio-3) was 5% by weight with respect to the nonvolatile content contained in the (ratio-3).

Reference Example 9 [Preparation Example 1 for Undercoat Paint]
94.5 parts by weight of the acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5, 7.4 parts by weight of “DICTON WHITE HD-8361W”, “SILAX PB-03” [( Shirasu Co., Ltd. Shirasu Balloon, average particle diameter: 75 μm, bulk density: 0.17 to 0.21] of a mixture of 2.2 parts by weight and 44 parts by weight of water was shaken with a paint conditioner for 30 minutes. A white undercoat paint (undercoat-1) having a PWC content of 10% by weight and a non-volatile content of 30% by weight was prepared. The Shirasu balloon content in the white undercoat paint (undercoat-1) was 5% by weight with respect to the nonvolatile content contained in the (undercoat-1).

Reference Example 10 [Preparation Example 2 for Undercoat Paint]
Acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5 94.5 parts by weight of the acrylic resin aqueous dispersion (W-2-1) obtained in Reference Example 5, and “DICTON WHITE HD” 7.4 parts by weight of “-8361W” and 2.2 parts by weight of “SILAX PB-05” [Shirasu Dou Shirasu balloon, average particle size: 40 μm, bulk density: 0.32 to 0.35] And 44 parts by weight of water were shaken with a paint conditioner for 30 minutes to prepare a white undercoat (undercoat-2) having a PWC of 10% by weight and a non-volatile content of 30% by weight. The Shirasu balloon content in the white undercoat paint (undercoat-2) was 5% by weight with respect to the nonvolatile content contained in the (undercoat-2).

Examples 1-4 and Comparative Examples 1-3
The irregular coating surface of several mm to several tens of mm is applied to the undercoat paints (undercoat-1) to (undercoat-2) and (relative-1) to (relative-3) prepared in Reference Examples 6 to 10. Each slate plate was coated with a flow coater method such that the average dry film thickness was 20 μm. Immediately after the coating, it was dried for 20 seconds with a hot air dryer at 160 ° C. to obtain a slate plate coated with a white coating film of various undercoat paints.

  The slate plate coated with an undercoating paint (undercoating-1) or (undercoating-2) had irregularities due to shirasu balloons on the surface of the undercoating film.

  The slate plate coated with an undercoat paint (ratio −1) and dried did not have unevenness due to the shirasu balloon on the surface of the undercoat coating film.

  The slate plate coated with an undercoat (ratio-2) and dried had irregularities due to the shirasu balloon.

  When the slate plate is coated with an undercoat paint (ratio-3) and dried, the film thickness of the undercoat film is larger than the average particle size of the shirasu balloon. I couldn't.

  Next, on each of the obtained slate plates, the black topcoat paints (topcoat-1) to (topcoat-2) prepared in Reference Examples 3 to 4 were each subjected to a flow coater method under the condition that the average dry film thickness was 5 μm. It was coated and immediately dried with a hot air dryer at 160 ° C. for 20 seconds to obtain various slate plates coated with a black coating film of top coating.

  Table 1 shows combinations of various undercoat paints and top coat paints thus obtained. Moreover, in Table 1, the evaluation results of visual observation of the coating film formation status of the top coat are also shown together.

<< Footnotes in Table 1 >>
The “coating film formation status” is a visual evaluation of the degree to which the base of the white coating film by the undercoat paint is shielded by the black coating film by the top coat paint. The evaluation criteria are as follows.
○: The white coating on the ground is completely shielded
Δ: Slightly visible white paint film
X: State in which the white coating film of the base is seen through at 10% or more of the slate plate area

Claims (4)

The coating film which has the unevenness | corrugation resulting from the said shirasu balloon on the said inorganic building material by apply | coating to the inorganic building material the undercoating coating containing the shirasu balloon which has an average particle diameter of 10-500 micrometers, and an acrylic resin aqueous dispersion, and drying it A coating film forming method in which a top coat is then applied and dried. The coating film forming method according to claim 1, wherein a film thickness of the concave portion in the coating film having unevenness caused by the shirasu balloon is 1/10 to ¾ of an average particle diameter of the shirasu balloon. The coating film forming method according to claim 1, wherein the shirasu balloon has a bulk density of 0.1 to 0.5. The coating film forming method according to claim 1, wherein the top coating contains a vinyl polymer having a structural unit derived from polysiloxane in a side chain and a curing agent.